Apparatus and methods for fabricating components

ABSTRACT

An additive manufacturing method for fabricating a component having a surface substantially free of imperfections may include providing a mold having a configuration corresponding to the component, and depositing a material on at least one surface of the mold to fabricate the component having the surface substantially free of imperfections.

TECHNICAL FIELD

Aspects of the present disclosure relate to apparatus and methods forfabricating components. In some instances, aspects of the presentdisclosure relate to apparatus and methods for fabricating components(such as, e.g., automobile parts, medical devices, machine components,consumer products, etc.) via additive manufacturing techniques orprocesses, which may be referred to as 3D printing manufacturingtechniques or processes.

BACKGROUND

Additive manufacturing techniques and processes generally involve thebuildup of one or more materials to make a net or near net shape (NNS)object, in contrast to subtractive manufacturing methods. Though“additive manufacturing” is an industry standard term (ASTM F2792),additive manufacturing encompasses various manufacturing and prototypingtechniques known under a variety of names, including freeformfabrication, 3D printing, rapid prototyping/tooling, etc. Additivemanufacturing techniques are capable of fabricating complex componentsfrom a wide variety of materials. Generally, a freestanding object canbe fabricated from a computer-aided design (CAD) model.

A particular type of additive manufacturing, or 3D printing, techniqueand process generally includes forming and extruding a bead of flowablematerial (e.g., molten thermoplastic), applying such bead of material ina strata of layers to form a facsimile of an article, and machining suchfacsimile to produce an end product. Such a process is generallyachieved by means of an extruder mounted on a computer numericcontrolled (CNC) machine with controlled motion along at least the X, Y,and Z-axes. In some cases, the flowable material, such as, e.g., moltenthermoplastic material, may be infused with a reinforcing material(e.g., strands of fiber) to enhance the material's strength. Theflowable material, while generally hot and pliable, may be depositedupon a substrate (e.g., a mold), pressed down or otherwise flattened tosome extent, and leveled to a consistent thickness, preferably by meansof a tangentially compensated roller mechanism. The flattening processmay aid in fusing a new layer of the flowable material to the previouslydeposited layer of the flowable material. In some instances, anoscillating plate may be used to flatten the bead of flowable materialto a desired thickness, thus effecting fusion to the previouslydeposited layer of flowable material. The deposition process may berepeated so that each successive layer of flowable material is depositedupon an existing layer to build up and manufacture a desired componentstructure. When executed properly, the new layer of flowable materialmay be deposited at a temperature sufficient enough to allow new layerof flowable material to melt and fuse with a previously deposited layerof flowable material, thus producing a solid part.

While the aforementioned process achieves a near net shape much fasterthan depositing down a large number of very thin layers, a surfacemilling or other finishing operation is required to achieve the finalnet shape of the article, since it is deposited in stepped layers oftamped, extruded material. Such milling or finishing generally isaccomplished using a rapidly spinning cutting tool with a round shapedtip, requiring numerous passes over the surface of the article, shiftingover a small distance after each pass to generate the desired surfacefinish. In order to achieve a smooth surface, the amount the tool pathis shifted after each pass must be relatively small; necessitating alarge number of passes, which in turn requires considerable time tocomplete. While this approach may be satisfactory for a single item or aprototype part, it is less desirable for the production of multipleidentical parts.

In view of the foregoing, the present disclosure provides systems andmethods for producing articles from thermoplastic or flowable materialusing additive manufacturing techniques, which can generate multiplearticles that are dimensionally accurate, and replicate the desiredshape and surface features in less time, less effort, and reduced cost.Consequently, the present disclosure provides aspects of methods andapparatus for producing dimensionally accurate articles, which embodysurface properties of sufficient quality, so as to negate the need forfinishing operations.

SUMMARY

Aspects of the present disclosure relate to, among other things, methodsand apparatus for fabricating components via additive manufacturing or3D printing techniques. Each of the aspects disclosed herein may includeone or more of the features described in connection with any of theother disclosed aspects.

In one embodiment, an additive manufacturing method for fabricating acomponent having a surface substantially free of imperfections mayinclude providing a mold having a configuration corresponding to thecomponent, and depositing a material on at least one surface of the moldto fabricate the component having the surface substantially free ofimperfections.

Embodiments of the additive manufacturing method may include one or moreof the following features: the at least one surface of the mold maydefine a cavity in the mold, and the at least one surface may include aconcave or convex configuration; the at least one surface may beprocessed to resist adhesion of the material to the at least onesurface; the surface substantially free of imperfections may be formedwithout a finishing step; the mold may be configured to control acooling rate of the material deposited on the at least one surface ofthe mold; the step of depositing the material on the at least onesurface of the mold may include extruding the material onto the at leastone surface from a nozzle; the at least one surface may include aplurality of curves, and the nozzle may be configured for movementrelative to the at least one surface such that a centerline of thenozzle remains perpendicular to a tangent plane for each curve of theplurality of curves; the nozzle may be configured to translate along afirst axis, a second axis perpendicular to the first axis, and a thirdaxis orthogonal to the first and second axes, and wherein the nozzle maybe configured to rotate in a plane defined by the first and second axes;depositing the material on the at least one surface of the mold mayinclude depositing a plurality of material beads adjacent to oneanother; the material may include a thermoplastic having a reinforcingmaterial therein; the reinforcing material may include strands of fiber;depositing the material on the at least one surface of the mold mayinclude fusing the material to an adjacent previously deposited bead ofmaterial; the nozzle may be part of a programmable computer numericcontrol (CNC) machine; and depositing the material on the at least onesurface of the mold may include depositing the material in a pattern,wherein the pattern is based on a digital representation of thecomponent.

In another embodiment, an additive manufacturing system for fabricatinga component having a surface substantially free of imperfections mayinclude a programmable computer numeric control (CNC) machine configuredto extrude a flowable material. The additive manufacturing system mayfurther include a mold having a cavity defining at least one surface forreceiving a plurality of beads of the flowable material.

Embodiments of the additive manufacturing method may include one or moreof the following features: the computer numeric control (CNC) machinemay be configured to deposit the flowable material in a pattern based ona digital representation; the programmable computer numeric control(CNC) machine may include a nozzle for extruding the flowable material,and wherein the nozzle may be moveable along a first axis, a second axisperpendicular to the first axis, and a third axis orthogonal to thefirst and second axes, and wherein the nozzle may be configured torotate in a plane defined by the first and second axes; the at least onesurface may include a plurality of curves, and wherein the nozzle may beconfigured for movement relative to the at least one surface such that acenterline of the nozzle remains perpendicular to a tangent plane foreach curve of the plurality of curves; the mold may include at least oneheating element configured to control a rate of cooling of the flowablematerial; and the material may include a thermoplastic.

As used herein, the terms “comprises,” “comprising,” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises a list ofelements does not include only those elements, but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. The term “exemplary” is used in the sense of“example,” rather than “ideal.”

It may be understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary aspects of the presentdisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 is a perspective view of an exemplary CNC machine operablepursuant to an additive manufacturing process in forming articles,according to an aspect of the present disclosure;

FIG. 2 is an enlarged perspective view of an exemplary carriage andapplicator assembly of the exemplary CNC machine shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view of an exemplary materialapplicator head mounted on a lower end of the applicator assembly ofFIG. 2, illustrating a bead of flowable material being extruded throughan applicator nozzle onto a work surface, and a roller engaging andcompressing a portion of such bead against such work surface, forming aply of an article being manufactured, according to an aspect of thepresent disclosure;

FIG. 4 is a perspective view of an exemplary mold for fabricatingcomponents, according to an aspect of the present disclosure;

FIG. 5 is a perspective view of the mold of FIG. 4 partially coveredwith a layer of flowable material deposited therein and receiving anadjoining shaped bead of flowable material from a material applicatorhead of an exemplary CNC machine;

FIG. 6 is a side view of an application head, shown in a positionwherein the centerline of the application head is perpendicular to thetangent plane of the contoured surface onto which the molten material isbeing deposited;

FIG. 7A is a perspective view of an exemplary completed component formedin the mold of FIG. 4, illustrating the application side of thecomponent; and

FIG. 7B is another view of the FIG. 7A component, showing the inverseside of the component, the surface of which is replicated substantiallywithout objectionable surface imperfections.

DETAILED DESCRIPTION

The present disclosure is drawn to, among other things, methods andapparatus for fabricating multiple components via additive manufacturingor 3D printing techniques. More particularly, the methods and apparatusdescribed herein produce components having at least one surfacesubstantially without (or free of) objectionable imperfections, therebyeliminating the need for additional finishing processes duringmanufacturing. Those of ordinary skill in the art will understand that asurface substantially without (or free of) objectionable imperfectionsmay be a surface ready for use or delivery to a consumer without needingany further processing, such as, e.g., machining, sanding, grinding,etc., to, e.g., remove the imperfections.

In one aspect, fabrication of components having at least one surfacesubstantially without objectionable imperfections is achieved byproviding an open face mold of substantial and stable substructure, of amaterial that can tolerate a heated thermoplastic material, and uponwhich layers of flowable material may be deposited and thus stabilized.Such a mold would have one or more of a concave or convex surface thatis the inverse of a surface of the article to be fabricated or otherwisereplicated. In forming such an article, instead of depositing materialin flat, horizontal layers as is traditionally done in the additivemanufacturing process, material is deposited onto the surface of theopen mold as the centerline of the application nozzle is maintained insubstantially perpendicular alignment with the variable tangent plane ofthe contoured surface. Such a process requires the use of a CNC machinewith controlled motion along the X, Y, and Z-axes, as well as anarticulated application head with controlled rotational displacementabout both the vertical and horizontal axes, essentially providing aflexible head at the output of the extruder through which the flowablematerial may be deposited upon a surface of the mold. After the flowablematerial has been deposited over the entire mold surface, and thematerial has cooled sufficiently to re-harden, the fabricated part canbe removed. Since the surface of the part that was in contact with themold has taken on the shape of the mold, which is the final shapedesired, no further machining operations may be necessary.

Referring to FIG. 1 of the drawings, there is illustrated a programmablecomputer numeric control (CNC) machine 1 embodying aspects of thepresent disclosure. A controller (not shown) may be operativelyconnected to the machine 1 for displacing an application head along alongitudinal line of travel or an x-axis, a transverse line of travel ora y-axis, and a vertical line of travel or a z-axis, in accordance witha program inputted or loaded into the controller for performing anadditive manufacturing process to replicate a desired component. CNCmachine 1 may be configured to print or otherwise build 3D parts fromdigital representations of the 3D parts (e.g., AMF and STL format files)programmed into the controller. For example, in an extrusion-basedadditive manufacturing system, a 3D part may be printed from a digitalrepresentation of the 3D part in a layer-by-layer manner by extruding aflowable material. The flowable material may be extruded through anextrusion tip carried by a print head of the system, and is deposited asa sequence of beads on a substrate in an x-y plane. The extrudedflowable material may fuse to previously deposited material, and maysolidify upon a drop in temperature. The position of the print headrelative to the substrate is then incremented along a z-axis(perpendicular to the x-y plane), and the process is then repeated toform a 3D part resembling the digital representation.

Machine 1 includes a bed 20 provided with a pair of transversely spacedside walls 21 and 22, a gantry 23 supported on side walls 21 and 22,carriage 24 mounted on gantry 23, a carrier 25 mounted on carriage 24,and an applicator assembly 26 mounted on carrier 25. Supported on bed 20between side walls 21 and 22 is a worktable 27 provided with a supportsurface disposed in an x-y plane, which may be fixed or displaceablealong an x-axis. In the displaceable version, the worktable may bedisplaceable along a set of rails mounted on the bed 20 by means ofservomotors and rails 29 mounted on the bed 20 and operatively connectedto the worktable 27. Gantry 23 is disposed along a y-axis, supported atthe ends thereof on end walls 21 and 22, either fixedly or displaceablyalong an x-axis on a set of guide rails 28 and 29 provided on the upperends of side walls 21 and 22. In the displaceable version, the gantry 23may be displaceable by a set of servomotors mounted on the gantry 23 andoperatively connected to tracks provided on the side walls 21 and 22 ofthe bed 20. Carriage 24 is supported on gantry 23 and is provided with asupport member 30 mounted on and displaceable along one or more guiderails 31, 32 and 33 provided on the gantry 23. Carriage 24 may bedisplaceable along a y-axis on one or more guide rails 31, 32 and 33 bya servomotor mounted on the gantry 23 and operatively connected tosupport member 30. Carrier 25 is mounted on a set of spaced, verticallydisposed guide rails 34 and 35 supported on the carriage 24 fordisplacement of the carrier 25 relative to the carriage 24 along az-axis. Carrier 25 may be displaceable along the z-axis by a servomotormounted on the carriage 24 and operatively connected to the carrier 25.

As best shown in FIG. 2, carrier 25 is provided with a base platform 36,a gear box 37 fixedly mounted on the upper side thereof, and a mountingplatform 38 rotatably mounted on the underside of base platform 36.Platform 38 may be provided with openings therethrough disposed alongthe z-axis of the carrier 25. Gear box 37 may be provided with a geararrangement having an opening therethrough and disposed coaxially withthe aligned openings in gear box 37 and platforms 36 and 38, operativelyconnected to platform 38 for rotation about the z-axis and rotatableabout such axis by means of a servomotor 39 mounted on base platform 36and operatively connected to such gear arrangement.

Applicator assembly 26 may include an upper segment 41 and a lowersegment 42. Upper segment 41 includes a transverse portion 41 a securedto the underside of mounting platform 38 for rotational movement aboutthe z-axis. Upper segment 41 may be provided with an openingtherethrough along such z-axis, and a depending portion 41 b may bedisposed substantially laterally relative to such z-axis. Lower segment42 includes a housing 42 b disposed on an inner side of dependingportion 41 b. Housing 42 b may be mounted on a shaft journalled in alower end of depending portion 41 b, intersecting and disposedperpendicular to the z-axis of carrier 25, and further housing 42 b maybe provided with a laterally projecting application head 43 at a freeend thereof. Mounted on a gearbox 44 provided on an outer side ofsegment portion 41 b is a servomotor 45 operatively connected throughgearbox 44 to the shaft journalled in portion 41 b. Servomotor 45 may beconfigured for pivotally displacing lower segment 42 in a y-z plane. Amaterial tamping roller 59 (shown in FIG. 3), rotatably mounted incarrier bracket 47, provides a means for flattening and leveling a beadof flowable material (e.g., molten thermoplastic), as shown in FIG. 3.Carrier bracket 47 may be adapted to be rotationally displaced by meansof a servomotor 60 (shown in FIG. 2), through a sprocket 56 anddrive-chain 65 arrangement.

With continuing reference to FIG. 3, application head 43 may include ahousing 46 with a roller bearing 49 mounted therein. Carrier bracket 47is fixedly mounted to an adaptor sleeve 50, journalled in bearing 49. Asbest shown in FIGS. 2-3, a conduit 52 consisting of an elongated,flexible material for conveying, e.g., a molten bead of a flowablematerial (e.g., molten thermoplastic) under pressure from a sourcedisposed on carrier 25 or another source, to applicator head 43, may befixedly (or removably) connected to, and in communication with nozzle51. An intermediate portion of conduit 52 may be routed through theopenings through gear box 37, support platform 36 and mounting platform38, and along the z-axis of carrier 25. In use, the flowable material 53(e.g., thermoplastic) may be heated sufficiently to form a molten beadthereof, which is then forced through conduit 52 and extruded throughapplicator nozzle 51, to form multiple rows of deposited material 53 inthe form of molten beads, as described herein. Such beads of moltenmaterial 53 may be flattened, leveled, and/or fused to adjoining layersby any suitable means, such as, e.g., bead-shaping roller 59, to form anarticle. Even though bead-shaping roller 59 is depicted as beingintegral with applicator head 43, bead-shaping roller 50 may be separateand discrete from applicator head 43. In some embodiments, the depositedmaterial 53 may be provided with a suitable reinforcing material, suchas, e.g., fibers that facilitate and enhance the fusion of adjacentlayers of extruded flowable material 53.

In some examples, machine 1 may include a velocimetry assembly (ormultiple velocimetry assemblies) configured to determine flow rates(e.g., velocities and/or volumetric flow rates) of material 53 beingdelivered from applicator head 43. The velocimetry assembly preferablytransmits signals relating to the determined flow rates to theaforementioned controller coupled to machine 1, which may then utilizethe received information to compensate for variations in the materialflow rates.

In the course of fabricating a component, pursuant to the methodsdescribed herein, the control system of the machine 1, in executing theinputted program, would operate the several servomotors as described todisplace the gantry 23 along the x-axis, displace the carriage 24 alongthe y-axis, displace the carrier 25 along a z-axis, pivot lowerapplicator segment 42 about an axis disposed in an x-y plane and rotatebracket 47 about a z-axis thereof, in accordance with the inputtedprogram, to provide the desired end product or a near duplicate thereof.A suitable mold (e.g., mold 62) is provided for depositing flowablematerial 53 thereon. Such a mold 62 may include at least one surfacethat is the inverse of the article to be produced, in essence, either aconvex mold, or a concave mold, commonly referred to as a male mold or afemale mold.

With reference now to FIG. 4, there is depicted an exemplary female mold62, with a machined cavity, exemplary of a mold that may be used forforming, e.g. a vehicle engine-compartment lid. Mold 62 may be anysuitable mold known in the art, including, but not limited to, moldsformed by additive manufacturing or 3D printing processes. In someexamples, mold 62 may include a solid body 63 and a cavity 64 formedtherein. Cavity 64 may be formed by any suitable means known in the art,including, e.g., machining processes. One or more surfaces of cavity 64maybe suitably prepared so as to prevent the adhesion of any moltenthermoplastic material deposited thereon. For example, the one or moresurfaces may be provided with a suitable coating and/or polished orotherwise finished so as to prevent molten thermoplastic from stickingto the one or more surfaces of cavity 64. In some embodiments, mold 62may be configured to facilitate cooling or warming of material depositedthereon. For example, mold 62 may include one or more channels (notshown) disposed therein for circulation of cooled or heated fluid. Thechannels may be disposed in any suitable configuration to sufficientlyheat or cool material (e.g., flowable material 53) deposited in cavity64. In addition, or alternatively, mold 62 may be provided with one ormore heating elements, such as, e.g., resistive heating elements,configured to warm mold 62 so as control a rate of cooling of materialdeposited in cavity 64.

Referring now to FIG. 5, with the machine suitably programmed andactivated based on a selected profile relating to a part targeted forfabrication, beads of flowable material 53 may be extruded ahead of thepath of roller 59, onto the machined or otherwise suitable preparedsurface of cavity 64 of mold 62, accurately replicating the surfacethereof and fusing laterally to adjoining, previously deposited beads,forming a single fused layer, thus forming an article that complementsone or more surfaces of cavity 64. As best shown in the partial,sectioned view in FIG. 6, the engagement and compression of the bead byroller 59 compresses the bead of extruded material against the surfaceof said mold, as the application head 43 is pivoted to maintainsubstantial perpendicularity between the nozzle centerline and thetangent plane of the contoured surface of cavity 64 of mold 62. Stateddifferently, the application head may be rotated or otherwise displacedto remain perpendicular to a tangent plane of any curve (e.g., concaveor convex) of the surface of cavity 64. The surface of an article thuslyformed is an inverse duplication of the mold surface onto which it wasdeposited.

FIG. 7a exemplifies a vehicle engine-compartment lid 80, formed by themethods and apparatus described herein, as viewed from the depositionside 81, while FIG. 7b exemplifies the same item, as viewed from thefinished side 82, replicated with substantially no objectionable surfaceimperfections. If necessary, only minimal machining or suitablefinishing processes may be performed around the bottom periphery of suchan item, in order to provide for a suitably finished mating surface.

While principles of the present disclosure are described herein withreference to illustrative embodiments for particular applications, itshould be understood that the disclosure is not limited thereto. Thosehaving ordinary skill in the art and access to the teachings providedherein will recognize additional modifications, applications,embodiments, and substitution of equivalents all fall within the scopeof the embodiments described herein. Accordingly, the invention is notto be considered as limited by the foregoing description.

1.-20. (canceled)
 21. An additive manufacturing apparatus, comprising: amaterial guide configured to receive a thermoplastic material; anapplicator assembly connected to the material guide and connecteddownstream of the material guide; a nozzle connected to the applicatorassembly, the nozzle being positionable with the applicator assemblysuch that an axis of the nozzle forms a non-zero angle with a verticaldirection; and a roller that is positionable behind the nozzle, theroller configured to follow the nozzle and to press upon materialdeposited with the nozzle while the nozzle forms the non-zero angle withthe vertical direction.
 22. The additive manufacturing apparatus ofclaim 21, wherein the axis of the nozzle extends through an opening ofthe nozzle that is positionable ahead of the roller.
 23. The additivemanufacturing apparatus of claim 21, wherein the applicator assemblyincludes a sprocket configured to change a position of the roller. 24.The additive manufacturing apparatus of claim 23, wherein the roller issecured to the applicator assembly with a bracket assembly.
 25. Theadditive manufacturing apparatus of claim 24, wherein the sprocket isconfigured to change a position of the roller together with the bracketassembly.
 26. The additive manufacturing apparatus of claim 25, furtherincluding a servomotor that changes the position of the roller with thebracket assembly via the sprocket.
 27. The additive manufacturingapparatus of claim 21, wherein the material guide has an upstreamportion and a downstream portion, the upstream and downstream portionsforming different angles with respect to the vertical direction.
 28. Theadditive manufacturing apparatus of claim 27, wherein the nozzle definesan axis, the upstream portion extending at an angle with respect to theaxis and the downstream portion extending in alignment with the axis.29. An additive manufacturing apparatus, comprising: an applicatorassembly; a nozzle connected to the applicator assembly; a compressionroller; a bracket connected to the compression roller to secure thecompression roller to an end face of the applicator assembly, theapplicator assembly being connected to a material guide extending fromthe nozzle; and a sprocket connected to the applicator assembly, thesprocket being configured to change a relative position of thecompression roller as compared to the nozzle.
 30. The additivemanufacturing apparatus of claim 29, wherein the relative position ofthe compression roller as compared to the nozzle is an angular positionaround an axis that extends through an opening of the nozzle.
 31. Theadditive manufacturing apparatus of claim 29, further comprising a motorconfigured to displace the nozzle and the compression roller in avertical direction.
 32. The additive manufacturing apparatus of claim31, further including a surface configured to receive material depositedwith the nozzle, the surface having a height that changes along avertical direction.
 33. The additive manufacturing apparatus of claim32, wherein the bracket extends between the end face of the applicatorassembly and the surface when the nozzle faces the surface so as todeposit the material on the surface.
 34. An additive manufacturingapparatus, comprising: an applicator assembly including a nozzle; amaterial guide configured to guide thermoplastic material to an openingof the nozzle; a surface configured to receive the thermoplasticmaterial; a compression device configured to follow the nozzle and tocompress deposited thermoplastic material; and a sprocket configured tomove the compression device.
 35. The additive manufacturing apparatus ofclaim 34, wherein the compression device includes a compression rollersecured to an end of the applicator assembly.
 36. The additivemanufacturing apparatus of claim 35, further including a carrier thatsupports the applicator assembly, the carrier being movable in avertical direction with the nozzle and the compression device.
 37. Theadditive manufacturing apparatus of claim 34, wherein the opening of thenozzle is positionable together with the applicator assembly, such thatthe nozzle defines a longitudinal axis extending through the opening ofthe nozzle and through a portion of the material guide, the longitudinalaxis forming a non-zero angle with respect to a vertical direction. 38.The additive manufacturing apparatus of claim 37, wherein the nozzle isconfigured to translate along a first axis, a second axis orthogonal tothe first axis, and a third axis orthogonal to the first and secondaxes, and wherein the nozzle is configured to rotate in a plane definedby the first and second axes.
 39. The additive manufacturing apparatusof claim 34, wherein a portion of the material guide extends through theapplicator assembly and terminates at the opening of the nozzle.
 40. Theadditive manufacturing apparatus of claim 34, wherein, the compressiondevice is connected to the applicator assembly via a bracket, thebracket being secured to the sprocket.